Return-Path: Received: (qmail 31011 invoked from network); 17 Dec 2002 12:16:18 -0000 Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 17 Dec 2002 12:16:18 -0000 Received: (qmail 19019 invoked by uid 10001); 17 Dec 2002 12:16:17 -0000 X-MSMail-Priority: High Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 17 Dec 2002 12:16:17 -0000 X-SQ: A X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18OGaL-0002nS-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 17 Dec 2002 12:12:29 +0000 Received: from [212.1.130.1] (helo=smtp-1.visp.telinco.net) by post.thorcom.com with esmtp (Exim 4.10) id 18OGaK-0002nJ-00 for rsgb_lf_group@blacksheep.org; Tue, 17 Dec 2002 12:12:28 +0000 Received: from [80.40.93.29] (helo=standalone) by smtp-1.visp.telinco.net with smtp (Exim 3.32 #1) id 18OGQ0-0000qb-00; Tue, 17 Dec 2002 12:01:49 +0000 Received: by localhost with Microsoft MAPI; Tue, 17 Dec 2002 12:12:06 -0000 Message-ID: <01C2A5C5.83F0C550.g4jnt@thersgb.net> From: "Andy talbot" To: rsgb_lf_group@blacksheep.org Cc: Clive.Kidd@dstl.gov.uk Date: Tue, 17 Dec 2002 12:12:01 -0000 Importance: high X-Priority: 1 X-Mailer: Microsoft Internet E-mail/MAPI - 8.0.0.4211 MIME-Version: 1.0 Subject: LF: Coil Losses Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=1.2 required=5.0tests=SPAM_PHRASE_00_01,X_PRIORITY_HIGHversion=2.42 X-Spam-Level: * Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group To add to the confusion a little. Has anyone noticed the change in coil (or loop) Q that is going to occur over temperature ? By my reckonning, over the temperature reange 0 deg to 40 deg (in a shed in a hot summer) the DC copper resistance will go up by 16%. (temperature coefficient of Cu at 20 deg = 0.0039, delta R = 1.0039 ^ 40) Assuming RF loss is only related to skin depth, and this changes as the square root of resistivity that suggests coil Q could to be 8% higher on cold winter days. I know coil losses are usually swamped by ground losses, but it may just be observable by loop owners. Andy G4JNT